Duffer (noun)

1. A person who is not skilled or competent at something.
2. A person who is considered to be a fraud or cheat.

Origin:

The word "duffer" is of uncertain origin, it could be from a dialect word, or from british slang word meaning a "fraud" or "cheat".

Examples:

1. He's a duffer at golf, but he keeps trying.
2. The company was run by a bunch of duffers who knew nothing about the industry.
3. He was caught out as a duffer when he couldn't answer basic questions.
4. The new employee turned out to be a duffer, not able to perform the job.
5. He was a duffer, pretending to be an expert in the field.